How can I get numbers, operators and braces from regular expressions in C#?

Question

string[] num = Regex.Split(expr, @"\(|\)|\-|\+|\*|\/").Where(s => !String.IsNullOrEmpty(s)).ToArray();

为此，我得到了运算符和括号 。

Answer 1

Use lookaround ie lookahead and lookbehind to split the input

 (?<=\(|\)|\-|\+|\*|\/)|(?=\(|\)|\-|\+|\*|\/)
                       ^

Without lookaround the regex engine would split on those characters and eat it ie it won't show it in the result

If you want to evaluate mathematical expressions,have a look at these

• Is there a string math evaluator in .NET?

• Create Binary Tree from Mathematical Expression